The effect of various types of splenectomy on the development of B-16 melanoma in mice.

260 CB57BL/J6 mice were used in an experimental protocol designed to investigate the effects of 4 different varieties of splenectomy on the growth rate of subcutaneously implanted GB-16 melanoma. In addition, the mean and absolute survival of the mice, the histopathology of the tumour and the effects of the same procedures on the immunological status of the tumour-bearing animals as assessed by serum IgG levels and immunoelectrophoresis were determined. The effects of the timing of the splenectomy and the removal of the primary tumour after splenectomy on the above parameters were also annotated. The following were found: First, splenectomy performed 1 week after B-16 melanoma tumour implantation in mice i.e. in the early period of oncogenesis, lengthened the survival of the grafted experiments, delayed tumour growth, reduced the "activity" of the tumour and caused pseudoencapsulation of the tumour by fibrous tissue. It increased, but not by a statistically significant degree (p > 0.05), the circulating levels of the IgG immunoglobulin. Second, splenectomy performed 4 weeks prior to grafting of the same tumour did not affect the circulating IgG levels, nor did it prolong survival; however, it reduced the rate of tumour growth and pseudoencapsulation of the tumour was observed. Third, splenectomy at the early stages of oncogenesis in combination with surgical removal of the primary tumour increased absolute and mean survival, delayed the tumour growth rate, increased the time to relapse and reduced the "activity" of the pseudocapsulated tumour.